Pivot polisher



Mar. 20, 1923.

C. CULMAN.

PIVOT POLISHER. FILED JAN. :9. 1920.

QL/w3 Patented 2Q, 1925.

entren stares maree CARL CULT/AN, OF HUNTINGTON PARK, CALIFORNIA. i

PIVOT POLISHER.

Application filed January 19, 1920. Serial No. 352,600.

To all whom t may concern:

Be it known that l, CARL CULMAN, a citizen of thelUnited States, and residing in the city of Huntington Park, California, have invented the new and useful Improvement in Pivot Polishers, of which the following is a specilication.

This invention relates to abrading devices adapted particularly to polish pivots of watches, etc.

rilhe operations on parts of watches and the like are delicate operations; accordingly, the conditions encountered are different entirely from those encountered in mechanical operations generally and accordingly, re quire delicate mechanisms. This is especially true since the abrading operations are usually on pivot parts in which 'the material removed must not only be small, but the pressure on the part operated upon must be very light.

One of the objects of this invention, therefore, is to provide an abrading device which is capable of performing thedelicate operations on the delicate parts of mechanisms.

Another object is to provide an abrading device which is simple in construction, effective in its operation, and can be used on an ordinary jewelers lathe, and with an ordinary balance chuck.

Further objects will appear from the detail description takenv in connection with the accompanying drawing, in which:

Figure 1 is a side` elevation showing a part of the jewelers lathe, a balance chuck and illustrating the' abrading element embodying this invention; j j

Figures 2 and 3 are sections on the line 2-2, Figure 1, illustrating the operations, and y n Figures d to 7 inclusive are diagrammatic views illustrating the operation.

Referring to the accompanying drawing, and more particularly to Figures 1v to 3 inelusive,` 1 designates a bed of an ordinary jewelers lathe having a head stock 2, a tail stock 3 provided with the usual clamping device l and with any suitable adjusting device 5 for throwingthe spindle 6 laterally oli'l center. The live spindle is provided with a balance chuck 8, such as shown in United States Patent No. 760,314, granted May `17 1904. This balance chuck is provided with `a removable cap9 providing a side face 10 and having also a central aperture through which projects the balance pivot 11 of a balance arranged 'withinthe hollowchuclr. The pivot 11 is shown considerably enlarged for the sake of clearness, but in practice, it will be very small.

Arranged to be forced on and retained on the spindle 6 is a collar 12 which carries a head 13 providedwith spaced arms or lugs 1e bored to receive ashaft 15. yThis shaft has mounted thereon a driving element 16 providedwith a friction facing 17 of cork or the like adapted to bear against the side face 10 of the chuck. This driving element is arranged to have a frictional connection with the shaft 15 by ilorcing the yshaft into a yielding bushing 18 on the driving` element. 4Mounted also on the shaft is an abrading element comprising a grinding part 19 and a polishing part 20, either one of which is arranged to engage the work 11 as shown respectively in Figures 2 and 3. This abrading element also has a yielding sleeve or bushing 21 so as to provide a frictional connection between the shaft and the element.

TWhen the shaft 15 is set radially so that the center thereof will intersect the center or rotation of the chuck 8 as shown in Figure 2, and if the driving element is now movedv against the face 10 so that the shaft 15 will be revolved as the chuck revolves carrying the abrading element with it, the forces are such that the abrading element will have a radially outward pull vexerted thereon, no matter inwhich direction the chuck rotates.

This will be clear from a consideration of the diagrams, Figures 4; and 5. Assuming that the direction of vrotaton of the chuck is as indicated by the direction of the arrows, Figures 4 and 5, thereby causing rotation of the abrading element in the direction of the arrow; the friction surface 17 will be slightly flattened at the point of Contact as shown in Figure 4 and the pressure between the leading portions a of the point of contact andthe center c will be greater than the pressure between the lagging side Z) and the center c. Now in view of the fact that every particle when traveling from a to b will travel on the arcsof a circle d, Figure 5, which arcs lie in the face 10 of the chuck 8, there are two forces acting on this particle as it travels from a to namely a force e-f tending to move the particle outwardly radially and a force tending to move the particle inwardly radially. ln `view of the fact, however, that, as explained above, the pressure between t and c is greater than between Z) and c, e-f is greater than f-g; accordingly, the radial resultant of the force eis greater than the radial resultant f-z' of the force jl-g; accordingly, there is a net resultant force )li-e' tending to move each particle of the surface li', in contact with the surface l of the chuck outwardly. This is true no matter what the` direction of rotation of the chuck may be. Accordingly, it is true where the direction of rotation of the chuck is as shown in Figure 2,

This 4featiivre causes a radial outward movement of the shaft l5 as it is rotated thereby tending to carry the abrading element with it; accordingly, the abrading head is retained yieldingly against the work 1l so that the work will be abraded.

' In many classes of work, it is necessary to provide for two operations, namely a grinding operation and apoli'shing operation, and itis vfor this purpose that the abrading element is provided with a grinding part 19 and the polishing part 20. rIhe grinding andpolishing parts can' be interchangeably rendered efectiveyby reversing the abrading element; this however, takes time and may also'. interfere `with the delicate operations on the delicate parts operated upon. In Iaccordance with this invention, therefore, means are provided for selectively retaining either end of the' abrading element in engagement with the work without requiring detachment of that element.

Referringto Figure 3, the abrading element has been moved outwardly radially on the shaft lfso-that its polishing part will now engagethe work. In order, however, tok retain the polishing head in enga-gement with the work, the force applied to they shaft l5 must be reversed so that there will now beexerted an inward radial pressure on the shaft and on the abrading element. Thisl is accomplished as follows:

"Referring, first to Figure 6, assume that the medial contact point c is shifted to one side of the center, which can be accomplished by shifting the spindle 6 by manipulation of an adjusting device, such 5; it will be noted that if the direction of rotation is as indicated. in Figure 6, the resultant ff-i is in the same direction as h-f and accordingly, the radial force t-c' is the sum of the resultant forces instead of a difference of the `same as in Figure 5, when the line of contact passes through the center of rotation of the chuck ;v accordingly, when the chuck is'rotatediin the direction of the arrow 7, the resultant force on the connected driving and abradingL elements will be a radial outward force.

Assume now that the direction of rotation is as shown in Figure 3, then it will be clear from Figure 7 that the resultant force -h will now be a radial inward force. Accordingly, the pressure applied to the abrading head is such as to cause the polishing part 2O to press against the work.

In practice the direction of rotation of the polishing head is as indicated in Figures 2 and 3. When grinding as the first operation, the spindle 6 is set on center thereby causing the grinding part 19 to be pressed yieldinglyagainst the work to grind the same. In order now to polishthe work, the center is moved to the right, Figure l,

carrying Vthe abrading device with it, 'the spindle 6 is moved off-center, as shown in Figure 3, the abrading` element is moved up on the shaft l5 and the spindle G is moved to the left again, thereby causing the polishing part to now yieldingly engage the work,

to polish the same. rlChe same results may, however, be accomplished by initially setting the spindle 6 off center, when the ,operations may be readily obtained by the simple reversal of the rotation of the chuck.

In Figures 2 yand 3, the shaft l5 is arranged angularly on oppositesides of center; this is, however, not necessary since the direction of pressure is reversed irrespective of any angular position of the shaft 15,.since that is determined by the eccentricity.

It will, therefore, be seen that the invention accomplishes its objects. The device has such a structure as to enablethe delicate operations on the delicate parts` re-V quiring treatment. The frictional connection of the driving and abrading elements provides for a yielding pressure as well as a yielding abrading action. 'IVhe device is exceedingly simple in construction, cheap to manufacture, and can be., applied tothe "or-v dinary jewelers lathe,` and, .there fore, requires no added expense.

Itis obvious that various changes may be made, in the details of construction without departing from the'k spirit of.` this invention; it is, therefore, to be understoodthat this invention is not to be limited to the specific details shown and described.

lI claim-- l. A device of the class described, com,-`

work engaging partin engagement` with the work.

2. A device ofthe class described, `comprising, a rotary work holder, Van abrading element, a driven element connected with said abrading element and engagingthel side face of saidfholder, adapted upon such en-v gagement and by the action of the driving force transmitted by saiduholdento retain` said abrading element in engagement With the work.

8. A device of the class described, comprising', a rotary Work holder, and connected abrading and driven elements arranged radially of said holder with said driven element engaging the side face of said holder eccentrically thereof, whereby said driven element is adapted upon such engagement to retain said ab-rading element in engagement with the Work.

4l. A device of the class described, comprising, a rotary Work holder, and connected abrading and driving elements arranged radially of said holder `with said driving element engaging the side face of said holder eocentrically thereof, whereby said driving element is adapted upon suoli engagement and upon selective shifting of said driving element to selectively retain either face of said abrading element in engagement with the Work.

5. A device of the class described, comprising, a rotary face plate having a radial driving face, an abrading Wheel, a driven Wheel mounted With its axis substantially yradially of said plate with itsA periphery engaging the `driving face thereof, and a driving connect-ion between said Wheels.

6. A device of the class described, cornprising, a rotary face plate having a radial driving face, an abrading Wheel, ka driven Wheel mounted With its axis eccentric but substantially radially of said plate and with its periphery engaging the driving face thereof, and a driving connection between said Wheels.

In testimonywhereof I ai'ix my signature this 17th dayl of Sept., 1919.

- CARL CULMAN. 

